The purpose of this study is to evaluate the efficacy of modafinil as an adjunctive treatment for Alzheimer's Disease (AD)-related apathy, and to examine the impact of a reduction in apathy on performance of activities of daily living (ADLs) in patients and on burden experienced by their caregivers. Apathy is seen in up to 70% of patients with mild to moderate stage AD. Prior research in this laboratory has shown that apathy is related to failure on ADLs. Patients with apathy require more support and assistance thus placing a larger burden on their caregivers. Effective treatments for apathy in AD have not been identified. The proposed study will explore the efficacy of modafinil, a psychostimulant medication, used adjunctively with cholinesterase inhibitors (CHIs) in treatment of apathy in AD patients. It will also examine the effect of a reduction in apathetic symptomatology on patient ADL performance and caregiver burden. A double-blind placebo controlled design will be used. Fifty AD patients with apathy will be recruited and randomized into either the Standard Care (CHI only) or the Experimental (CHI +modafinil) group. Measures of apathy, ADL functioning and caregiver burden will be collected at study enrollment and after eight weeks of pharmacologic treatment. This research is expected to lead to a new pharmacologic treatment for apathy symptoms in AD, and better understanding of the relationship between apathy and functional status.